This invention relates to an electromagnetically driven diaphragm pump. More particularly, this invention relates to such a pump which provides a continuous low flow of fluid at a high pressure.
Oscillating pumps such as that shown in U.S. Pat. No. 5,915,930 are well known in the art, but they lack accuracy when a low flow rate is desired. Those pumps which can provide accuracy in low flow/high pressure applications are noisy because the pumping element moves from seat to seat, thereby generating noise at each end of the stroke. Moreover, these pumps require multiple seals to the atmosphere and cannot always be designed to be compact.
It is thus an object of the present invention to provide an electromagnetically driven diaphragm pump for continuous low flow, high pressure applications.
It is another object of the present invention to provide a pump, as above, which is quiet during operation.
It is a further object of the present invention to provide a pump, as above, in which the diaphragm seals the pump chamber.
It is an additional object of the present invention to provide a pump, as above, which is compact and economically manufactured.
These and other objects of the present invention, as well as the advantages thereof over existing prior art forms, which will become apparent from the description to follow, are accomplished by the improvements hereinafter described and claimed.
In general, a pump made in accordance with the present invention includes a housing having a pump chamber defined by at least one wall. An inlet area includes a valve which allows fluid to be received in the chamber, and an outlet area includes a valve which allows fluid to be discharged from the chamber. An armature carries a plunger, and a stop surface is positioned adjacent to one end of the plunger. Means are provided to bias the plunger toward the stop surface. A diaphragm which seals the chamber is carried by the other end of the plunger. An electromagnetic coil is provided which, when activated, moves the armature to overcome the force of the means to bias so that the diaphragm is moved into the chamber without engaging the wall of the chamber to discharge fluid through the outlet area. Upon deactivation of the coil, the means to bias moves the plunger toward the stop surface but the plunger does not engage the stop surface as fluid is drawn in through the inlet area and into the chamber.
A preferred exemplary pump incorporating the concepts of the present invention is shown by way of example in the accompanying drawings without attempting to show all the various forms and modifications in which the invention might be embodied, the invention being measured by the appended claims and not by the details of the specification.